Alternating current apparatus



June 2, 1936. RC. CLINKER 2,042,505 ALTERNATING CURRENT APPARATUS Filed April 5, 1932 Fig.1.

#0211 F/AAMENT VULTS Fig.4

(I1 & l /6 Q Q /7\ 8 AMPEPES Invent or" fieginald C. Ch'nker; Deceased,

Hilda Gray Clinker', Executr-ix His Attorney.

Patented June 2, 1936 PATENT OFFICE 2,042,505 ALTERNATING CURRENT APPARATUS Reginald C. England,

Clinker, deceased, late of Rugby, by Hilda Gray Clinker, executrix,

Bristol, England, assignor to General Electric Company, a corporation 01' New York Application April 5, 1932, Serial No. 603,376 In Great Britain March 20, 1931 4 Claims. (01. 117-346) which is less than that of the alternating current.

supply, the apparatus being devoid of any moving parts. It is the object of the invention to provide improved apparatus of this character which is simple in construction, eillcient in operation and inexpensive to manufacture.

The invention will be better understood from the following description taken in connection with the accompanying drawing, and its scope will be pointed out in the appended claims.

Referring to the drawing, Fig. l is a circuit diagram illustrating one form of the invention; 3 Fig. 2 shows two volt-ampere characteristics of the circuit shown in Fig.1; Fig. 3 is a circuit diagram illustrating a modified form of the invention; and Fig. 4 shows an impedance-ampere characteristic of the circuit shown inFig. 3. 25 Fig. 1 shows the capacitor l which for example may have a capacitance of l mf., the saturable core reactor 2 whose core 18 self-saturating, that is, it is saturated by the current flowing in the reactor rather than by the use of a separate saturating winding, which reactor for example would require 10 voltamperes at 110 volts, and the resistor 3 which has a positive temperature coefficient, such for example as a metal filament incandescent lamp, all connected in series circuit with a source of alternating current represented at 4, which, for example, may be a 60- cycle, 1l0-volt source. The capacitance of the capacitor l and the inductance of the reactor 2 are such that when the resistance of the lamp 3 is a minimum, namely, when it is not illuminated or has a minimum illumination, the circuit is in a resonant condition. However, when the resistance of the lamp is a maximum, namely, when it is brightly illuminated, the resulting reduced value of the current so changes the condition of saturation in the reactor that the circuit no longer is resonant, and the combination of the capacitor and inductor therefore constitutes a much higher impedance in the circuit.

The operation of the apparatus may be more easily understood by reference to Fig. 2 where curve 6 represents the volt-ampere characteristic of the circuit when the resistance of lamp 3 is a minimum, for example, 10 ohms, and curve 1 represents the volt-ampere characteristic when the resistance of the lamp is a maximum, for example, 50 ohms. Supposing the applied voltage is represented by the line 8, thenwhen the lamp has a minimum resistance the current flowing in the circuit will-have a value represented by the point of intersection 9. At this current value the degree of saturation of the reactor 2 is such that a resonant condition exists in the circuit. The. current flowing therein is accordingly high and the lamp reaches full brill0 liancy but only after a definite time lag due to its heat inertia. When the lamp filament finally reaches its maximum temperature the filament resistance will have increased, inasmuch as it has a positive temperature coefiicient, to its 5 maximum value which is assumed to be 50 ohms. The current now flowing in the circuit is represented by the point of intersection III on curve I, and this reduced current so alters the degree of saturation of reactor 2'that the circuit is detuned. Hence the impedance offered by a com- .bination of the capacitor 1 and reactor 2 rises to a relatively large value. This large impedance reduces the current in the lamp 3 to a minimum value but due to the heat inertia of the filament the temperature thereof does not drop immediately but requires a definite time interval to reach the minimum temperature. At this low temperature the resistance of the filament returns to the original low value and the cycle of operation is completed only to be repeated at regular intervals. Thus the root mean square or effective value of the alternating current in the circuit pulsates and the lamp flashes intermittently at auniform frequency which is not related directly to and is of much lower frequency than the frequency of the alternating current supplied.

In the modified form of the invention shown in Fig. 3, where the. capacitor and the reactor may be like those in Fig. 1 and the voltage of the source may be 150 volts the controlling resistor l2 has a negative temperature coefilcient,

such for example as a carbon filament incandescent lamp. In this case the capacitor I and the saturable core reactor 2 whose core is self-saturating are arranged in parallel and constitute under certain conditions an oscillation circuit. In this case also the additional controlling resistance l3 which may be 500 ohms is employed in series with the lamp l2, whose resistance may vary from 500 ohms hot to 1500 ohms cold.

For a better understanding of this arrangement reference is had to Fig. 4 where l5 represents the impedance-ampere characteristic of the circuit shown in Fig. 3. When the lamp resistance is a maximum, namely, when it is'not illuminated or when the illumination is a minimum, the current be that represented by the line I 6, and the point of intersection ll of this line with curve l5 represents the impedance offered by the oscillation circuit, for at this current value the degree of saturation of reactor 2 is such that the circuit is non-resonant and therefore offers low impedance to the lamp circuit. The lamp filament having become incandescent, the resistance of the lamp, since the filament has a negative temperature coefficient, is reduced to a minimum value and the resulting increased current in the lamp circuit raises the saturation of reactor 2 to the point where the oscillation circuit becomes resonant. This new value of current in the lamp circuit is represented by the line [8, and the point of intersection l9 thereof with curve l5 shows that the impedance of the circuit due to the resonant condition of the oscillatory circuit now is high. This high impedance causes the lamp current to fall to a point at which the lamp is no longer illuminated or at which the illumination is a minimum it being understood that the change in temperature of the filament lags behind the current flowing therein as was pointed out above in connection with the Fig. 1. The current in the lamp circuit upon returning to the low value causes the oscillation circuit to return to the non-resonant condition which existed at the beginning. This cycle of operation is repeated indefinitely with regularity and independently of the frequency of its supplied alternating current.

While in both forms of the invention the lamp flashes with a uniform frequency, the frequency depends upon the time lag in the heating of the filament of the lamp and may be varied by employing lamps of different heating inertia.

The particular embodiments described above have been chosen as illustrative of the invention and it will be apparent that various other modifications may be made without departing from the spirit and scope of such invention which modifications it is aimed to ,cover by the appended claims.

What is claimed as new and is desired to be secured by Letters Patent of the United States is:

1. An alternating current circuit in which the effective value of the current pulsates at a frequency less than the alternating frequency comprising a resistor whose resistance depends upon the temperature thereof, a capacitor and selfsaid capacitor and react'dn having constants such that that part of said cir'-. f

cult which includes the same becomes alternately;

resonant and non-resonant at a frequency C0111;

trolled by the heat inertia of said resistor.

2. An alternating current circuit the current of which has a pulsating effective value comprisfing a capacitor, a self-saturating reactor and a. resistor having a positive temperature coefficient connected together in series and arranged to be energized from a source of alternating current, said capacitor and reactor having constants such that said circuit passes through alternate periods of resonance and non-resonance, the frequency of said periods being controlled by the heat inertia of said resistor.

3. Alternating current apparatus for producing intermittent light flashes comprising a capacitor, a self-saturating reactor and an incandescent lamp having a positive temperature coeflicient connected in a series circuit and arranged to be energized from a source of supply of alternating current, said capacitor and reactor having constants such that the change in resistance of said resistor in response to the current therein causes said circuit to become alternately resonant and non-resonant, the heat inertia of the resistor controlling the frequency of the periods of resonance and non-resonance.

4. Alternating current apparatus for producing intermittent light flashes comprising a capacitor; a self-saturating reactor and an incandescent lamp having a negative temperature coefficient, the capacitor and reactor being connected in parallel with each other to form an oscillation circuit and in series with the lamp and the apparatus being arranged to be energized from a source of supply of alternating current, said capacitor and reactor having constants such that said oscillation circuit becomes alternately resonant and non-resonant in response to the variations in resistance of the resistor, the frequency of the periods of resonance and non-resonance being controlled by the heat inertia of said resistor.

HILDA GRAY CLINKER, Sole Executria: 0f the Estate of Reginald C.

C'lz'nlcer, Deceased. 

